1. Field of the Invention
The present invention relates to an exposure apparatus and an exposure method for exposing a substrate, and a method for producing a device.
2. Description of the Related Art
An exposure apparatus, which performs the multiple exposure for the substrate, is known as disclosed, for example, in Japanese Patent Application Laid-open No. 2001-297976 in relation to the exposure apparatus to be used in the photolithography steps.
In the multiple exposure, when a plurality of light source units are provided and/or a plurality of illumination systems are provided in order to illuminate a plurality of masks with exposure light beams respectively, there is such a possibility that the apparatus cost is increased and/or the exposure apparatus becomes large-sized.